1. Field of the Invention
This invention relates to hemi-alkali metal salts of 2-pyrrolidone-5-carboxylic acid and to methods for producing the same.
2. Description of Prior Art
Although mono-alkali salts of 2-pyrrolidone-5-carboxylic acid are known, the hemi-alkali metal salts of 2-pyrrolidone-5-carboxylic acid (hereinafter abbreviated as PCA .sup.. 1/2 Me), as far as the present inventors are aware, is a novel compound which has never been disclosed in the available literature. The object is to produce PCA.1/2 salt industrially, which is useful in obtaining high purity PCA or the salt thereof which can be used as a material for medicine or cosmetics.